US5473632A - Method of determining the complex pulse response of a radio system - Google Patents

Method of determining the complex pulse response of a radio system Download PDF

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Publication number
US5473632A
US5473632A US08/259,570 US25957094A US5473632A US 5473632 A US5473632 A US 5473632A US 25957094 A US25957094 A US 25957094A US 5473632 A US5473632 A US 5473632A
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matrix
radio channel
signal portion
sup
pulse response
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US08/259,570
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English (en)
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Peter Riedel
Martin Stumpf
Otmar Wanierke
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Rohde and Schwarz GmbH and Co KG
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Rohde and Schwarz GmbH and Co KG
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/005—Control of transmission; Equalising

Definitions

  • the present invention is directed to a method of determining complex pulse response of a radio channel, for instance the pulse response of radio channels of a digital mobile radio network (GSM network).
  • GSM network digital mobile radio network
  • the known measuring method requires a special standard signal generator at the transmitter end and is operative on condition that an unused radio channel is available. Therefore the known method is relatively expensive.
  • the object is achieved by a method of the present invention for determining the complex pulse response h of a radio channel, especially in a digital mobile radio network. From a selected signal portion of the wanted signal transmitted via the radio channel, the matrix S of this signal portion is determined at the transmitter end from preset data of this signal portion or from sample values obtained by sampling this signal portion. At the receiver end the vector e of this signal portion is determined by sampling this selected signal portion.
  • the pulse response is calculated by linear transformation in accordance with the following relationship:
  • S *T is a transposed complex conjugate matrix of the matrix S.
  • the training sequence signal portion of the mobile radio network is used as the selected signal portion for determining the pulse response of a radio channel of the digital mobile radio network.
  • S *T is a transposed complex conjugate matrix of the matrix S,N is the number of columns in the matrix S, ⁇ is a standard deviation of input noise and E is a diagonally dominant matrix.
  • a signal portion of the wanted signal transmitted via the radio channel is utilized for measuring and determining the complex pulse response so that any separate standard signal generator at the transmitter end is unnecessary. Moreover, in the method according to the present invention any interruption of the wanted signal transmission is unnecessary, and the measurement may be performed during normal operation of the radio network.
  • the method of the present invention is especially suitable for measuring the pulse response of radio channels of a digital mobile radio network (GSM network).
  • GSM network digital mobile radio network
  • the pulse response according to the method of the invention may also be determined only once from a single selected signal portion. However, it is preferred to perform several successive measurements with repetitive similar signal portions so that the measurement becomes more precise. It has been found particularly advantageous to perform this measurement with periodically repetitive signal portions, i.e. with signal portions which occur successively at equal time intervals, as applicable to the mentioned training sequence signal portion of the GSM network.
  • the invention makes use of the recognized fact that there is a linear relationship between the complex pulse response, the periodically repetitive preset signal portion of the transmitted wanted signal, and the signal measured at the receiver end, which relationship may be expressed as a matrix multiplication when considered in time-discrete fashion. It is thereby possible to calculate from the preset and the measured signals the complex pulse response in a simple way by a linear approach, and in accordance with a further improvement of the invention it has been found particularly advantageous when said calculation also takes into account a corresponding correction factor whereby errors due to noise in the measured received signal may be reduced.
  • FIG. 1 is a graph of an analog signal portion of a training sequence that is receive on a direct route
  • FIG. 2 is a graph of a signal portion offset relative to the FIG. 1 signal portion
  • FIG. 3 is a graph of a combined signal of the FIGS. 1 and 2 signals.
  • FIGS. 4a-4d depict equations for solving the received signals and time-discrete pulse responses.
  • FIG. 5 is a block diagram of a transmitter connected to a receiver via a radio channel in a digital mobile radio network for use with the present invention.
  • FIG. 5 schematically depicts a transmitter 10 connected to a receiver 12 via a radio channel 14 in a portion of the digital mobile radio network GSM.
  • FIG. 1 illustrates the analog signal portion between -T 0 and t 0 known as the so-called training sequence, and other message portions indicated in dashed lines are transmitted upstream and downstream of this signal portion. It shall be assumed that the pulse response of the radio channel is not longer than T 0 , i.e.
  • the propagation time of a signal which is transmitted on an alternate route from the transmitter to the receiver should not be longer than T 0 as compared to the signal which is transmitted direct between transmitter and receiver. Since this portion between -T 0 and 0 may become corrupted by the previous unknown signal portions, only the portion between 0 and t 0 of the total transmitted training sequence is measured at the receiver end out of the received training sequence, and the pulse response is calculated therefrom.
  • FIG. 1 illustrates the signal portion received on the direct route
  • FIG. 2 shows the signal portion which is somewhat offset by the propagation time T 1 relative to the first-mentioned signal portion
  • FIG. 3 illustrates the combined signal which is composed of these two signal portions and measured in the receiver.
  • the signal portion s and the pulse response h which relationship may be expressed in the form of a matrix multiplication by the equation of FIG. 4a.
  • the columns of the matrix S are the transmission sequences which are offset relative to time
  • the vector h is the time-discrete pulse response
  • the vector e is the received signal.
  • the predetermined training sequence portion according to FIG. 1 between -T 0 and t 0 is digitalized at the transmitter end, i.e. from this portion 237 digital samples s1 through s237 are for instance obtained by sampling (signal sampler 1b in FIG. 5).
  • the values s1 . . . s237 are complex. Real and imaginary portions correspond to the in-phase or quadrature components of an I/Q-demodulator required for the measurement. From these samples the matrix S is then set up for this training sequence portion in accordance with the following relationship: ##EQU1##
  • Another possibility of arranging the matrix S of this signal portion according to FIG. 1 at the transmitter end consists in that from the preset normal data (present data 26 in FIG. 5) of the training sequence the samples s1 . . . s237 of its analog complex envelopes are calculated.
  • the matrix S thus determined by measurement or by calculation is then stored in a memory means (memory 18 in FIG. 5) of a measurement receiver.
  • a computer (computer 22 in FIG. 5) which cooperates with the measurement receiver the complex pulse response h is then calculated in accordance with the formula specified in FIG. 4c from the stored matrix S, the complex conjugate matrix S *T and the vector e.
  • the matrix S thereof is determined at the transmitter end and the vector e of the receiver-end signal portion is determined by sampling at the receiver end and then the pulse response is calculated therefrom by computation in accordance with the specified equation.
  • the calculated pulse response may then be displayed (display 24 in FIG. 5) directly as a graph or may be stored for further use in a memory means. It is thereby possible without any interruption of the radio traffic operation for instance of a mobile radio network to determine and to analyze the signal transmission quality in the various radio channels. For the measurement at the receiver end any receiver will be suitable from the demodulated analog signal from which as shown in FIG. 3 the vector e may be determined direct by sampling.
  • the pulse response is calculated by using the relationship specified in FIG. 4d according to which an additional positive correction factor ⁇ with a diagonally dominant identity matrix E is inserted.
  • the factor ⁇ depends on the noise level. The larger ⁇ is selected to be, the better the stability with respect to the influence of noise, although the unbiasedness will deteriorate with increasing ⁇ . Therefore the correction factor e is matched with the respective receiving situation.
  • the input noise may be estimated by way of the received level, in case of a low incoming-signal level greater noise is assumed and hence the factor ⁇ is selected to be correspondingly larger.
  • the resulting matrix according to FIG. 4d will immediately be stored in the memory of the measurement receiver, the matrix having been formed by computation of the initially established matrix S. Thereby the subsequent calculation of the pulse response is facilitated.
  • the input noise at the receiver is measured which has a symmetrically Gaussian distribution of the real and imaginary portion.
  • the standard deviation ⁇ of this symmetrical Gaussian distribution is calculated from this measured input noise according to known mathematics (for instance see I. N. Bronstein, K. S.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Noise Elimination (AREA)
US08/259,570 1991-10-31 1994-06-14 Method of determining the complex pulse response of a radio system Expired - Fee Related US5473632A (en)

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Applications Claiming Priority (4)

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DE4135953.4 1991-10-31
DE4135953A DE4135953A1 (de) 1991-10-31 1991-10-31 Verfahren zum bestimmen der komplexen impulsantwort eines funkkanals
US96992992A 1992-10-29 1992-10-29
US08/259,570 US5473632A (en) 1991-10-31 1994-06-14 Method of determining the complex pulse response of a radio system

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5633860A (en) * 1993-04-08 1997-05-27 Ant Nachrichtentechnik Gmbh Reliablity-controlled data reception in receivers for TDMA mobile radio systems
AU688228B1 (en) * 1997-02-25 1998-03-05 Nokia Telecommunications Oy A system and method of estimating CIR
CN1300962C (zh) * 2002-12-31 2007-02-14 上海贝尔阿尔卡特股份有限公司 正交频分复用系统中均衡快衰落信道的方法及装置
US20090323776A1 (en) * 2008-05-13 2009-12-31 Metropolitan Area Networks, Inc. Communication System, Apparatus, And Methods

Families Citing this family (5)

* Cited by examiner, † Cited by third party
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DE4233222C2 (de) * 1992-10-02 1995-07-20 Siemens Ag Meßsystem (Channel Sounder) zur Untersuchung von Mobilfunkkanälen
DE19651244C2 (de) * 1996-12-10 1998-11-19 Ericsson Telefon Ab L M Kommunikationssystem und Verfahren zum Testen einer Kommunikationsvorrichtung
DE19651275C2 (de) 1996-12-10 1999-02-11 Ericsson Telefon Ab L M Kommunikationssystem und Verfahren zum Testen einer Kommunikationsvorrichtung
DE19651334A1 (de) * 1996-12-10 1998-06-25 Ericsson Telefon Ab L M Betriebstestvorrichtung und Verfahren zur Ausführung eines Betriebstests für ein zu testendes System
DE19741991C1 (de) * 1997-09-24 1999-05-06 Medav Digitale Signalverarbeit Verfahren zum Bestimmen einer richtungsaufgelösten komplexen Impulsantwort eines Funkkanals und Meßsystem

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US5191598A (en) * 1990-02-16 1993-03-02 Telefonaktiebolaget L M Ericsson System for reducing the affects of signal fading on received signals
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US5191598A (en) * 1990-02-16 1993-03-02 Telefonaktiebolaget L M Ericsson System for reducing the affects of signal fading on received signals
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"Breitbandige Ausbreitungsmessungen zur Charakterisierung des Funkkanals beim GSM-System", by G. Kadal, R. W. Lorenz, Frequenz No. 45 (1991) pp. 158-163.
"Ein System fur Ausbreitungsmessungen in MobilfunkkanalenGrundlagen und Realisierung", by S. Hermann, U. Martin, R. Reng, H. W. Schuβler, K. Schwarz, Kleinheubacher Berichte No. 34 (1991), pp. 615-624.
"Neues Verfahren zur Messung der Kanalstoβantwort und Tragersynchronisation in digitalen Mobilfunkkanalen", by W. Plagge, D. Poppen, Frequenz 44 (1990), pp. 217-221.
"Real-Time ML Estimation of Very Frequency-Selective Multipath Channels", by J.-P. de Weck, J. Ruprecht, IEEE Global Telecommunications Conference GLOBECOM '90, (Dec. 1990), pp. 1-6.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5633860A (en) * 1993-04-08 1997-05-27 Ant Nachrichtentechnik Gmbh Reliablity-controlled data reception in receivers for TDMA mobile radio systems
AU688228B1 (en) * 1997-02-25 1998-03-05 Nokia Telecommunications Oy A system and method of estimating CIR
WO1998038772A1 (en) * 1997-02-25 1998-09-03 Nokia Telecommunications Oy Channel impulse response estimation using singular value decomposition
CN1300962C (zh) * 2002-12-31 2007-02-14 上海贝尔阿尔卡特股份有限公司 正交频分复用系统中均衡快衰落信道的方法及装置
US20090323776A1 (en) * 2008-05-13 2009-12-31 Metropolitan Area Networks, Inc. Communication System, Apparatus, And Methods
WO2009140290A3 (en) * 2008-05-13 2010-02-25 Metropolitan Area Networks, Inc. Communication system, apparatus, and methods
US8345727B2 (en) 2008-05-13 2013-01-01 Metropolitan Area Networks, Inc. Communication system, apparatus, and methods

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EP0539750A3 (en) 1993-07-14
EP0539750B1 (de) 1996-11-27
EP0539750A2 (de) 1993-05-05
DE59207590D1 (de) 1997-01-09
DE4135953A1 (de) 1993-05-06

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